Some 2 million Muslim pilgrims gathered on Monday in the valley of Mount Arafat in Saudi Arabia for a day of prayer that marks the pinnacle of the annual hajj.

Pilgrims stood shoulder to shoulder for an emotional day of repentance and supplication at the site Muslims believe the Prophet Muhammad delivered his final sermon, calling for equality and for Muslims to unite. According to the hadiths, traditional collections of the prophet's sayings and anecdotes about his life, Muhammad also reminded his followers of women's rights and that every Muslim life and property is sacred.

Saudi Arabia is preparing to host the annual hajj pilgrimage beginning Sunday, as over 1.6 million Muslim faithful from abroad have arrived in the ultraconservative kingdom.

The pilgrimage represents one of the five pillars of Islam and is required of all able-bodied Muslims once in their life. In recent weeks, the faithful have arrived in Mecca from across the world, all chanting "Labayk Allahuma Labayk," or "Here I am, God, answering your call. Here I am."